Latitude, Longitude & GPS
Earlier this week, Steven Schmitdkey from the US Census Bureau came to talk to us about how to use the GPS he loaned to us, and about some things to keep in mind when we go to Mission Trails. He explained lots of things and I have to admit, there were so many terms I didn’t know.
A few terms that I didn’t understand too well are:
– Topographic maps
– Magnetic Declination
– True North
– Magnetic North
– Constellations, and Satellites, theodolite.
I went online and researched on it a bit more. From what I researched, I found that Topographic maps are maps with contour lines that shows detailed and accurate representations of cultural (such as pyramids) & natural (such as mountains) features on the ground. That was the most clearest description that I could understand. Magnetic Declanation is when the magnetic polarity of the North Pole shifts. True North is for compasses, and Magnetic North is electronic. Constellations are stars in the form of something. Satellites can be moons or the electronic man-made on that provides information on our coordinates on Earth. In this case, our Nav Star GPS uses 24 to 32 satellites. A theodolite is an instrument for measuring both horizontal and veritcal angles. Its used by land surveyors.
From that, GPS stands for Global Positioning System, which is basically using satellites to find a location through Longitude and Latitude. An example of using a GPS is Geocaching. GIS stands for Geographic Information System. It is used for mapping out a certain location, such as taking an aerial view of the place you’re at.
To begin using the GPS that Mr. Schmitdkey loaned to us, we first, turn it on.
The start up screen will appear. You want to be on the map screen most of the time.
The dot on the screen is called track. There are three parts for the menu:
1. GO TO
Press the escape key to make the menu disappear.
Press menu to reopen it.
1. Create Waypoint
2. In the view menu, erase any other tracks. Press ERASE TRACKS, then ESCAPE three times.
3. Create Waypoint 02
4. “CREATE” menu
Waypoints can be connected into a trail.
Latitude and Longitude describes any location on Earth. They are a kind of measurement, generally known as coordinates. Technically, they’re two angles measured in degrees (“minutes of arc” and “seconds of arc”). Latitude are horizontal lines on a map. One of the lines is or runs through the Equator. If the lines are north of the Equator, they are called Northern Latitude (or positive) and vise versa. Longitude, also known as meridians, extend from pole to pole. The lines are vertical on a map. West is negative for Longitude; East is positive. Prime Meridian is a Longitude that runs through Greenwich, New England.
**info from wikipedia, and http://www-istp.gsfc.nasa.gov/stargaze/Slatlong.htm**